I've seen a number of questions about using JS to get detailed information about the OS. But I just want to know if I'm on Windows or not - my browser plugin will initially support Windows only so I don't want to make users pointlessly download a EXE/MSI installer.

I thought you could do some things like this without using JS... I've seen weird conditional HTML to detect IE in old books IIRC.

what 70% is low now? I don't accept answers just to boost my rating and I refuse to pander to people who only answer questions to get points.
–
Mr. BoyMar 3 '11 at 17:05

no it's the way you mark a question as answered. You vote an answer as helpful. If you're only answering my questions for points, I'd rather you saved your time. And commenting on my question just to complain when you don't submit an answer yourself makes you seem rather petty. Do you spend your time trawling new questions as some self-appointed policeman?
–
Mr. BoyMar 3 '11 at 17:54

that weird [if IE 6] syntax is what I was thinking of. But isn't that for browser only... how do you determine FireFox on Windows Vs Linux for example? Do you have a good link on these?
–
Mr. BoyMar 3 '11 at 17:07

That's what JS is for. I'll post a function in a second.
–
BlenderMar 3 '11 at 17:08

If you're not using javascript, the only thing I can think of is taking advantage of IE Conditional comments, but even then, that will only allow you to include/exclude some javascript or css.

If you really want to know the OS, browser, etc. you could try parsing the user-agent string. It reports on the browser, operating system, and other values, but it isn't reliable (for example, you can forge the string). Quirksmode has a good function to detect the browser and OS.